Defining complementary tools to the IVI. The Infrastructure Degradation Index (IDI) and the Infrastructure Histogram (HI)

[EN] The Infrastructure Value Index (IVI) is quickly becoming a standard as a valuable tool to quickly assess the state of urban water infrastructure. However, its simple nature (as a single metric) can mask some valuable information and lead to erroneous conclusions. This paper introduces two complementary tools to IVI: The Infrastructure Degradation Index (IDI) and the Infrastructure Histogram (HI). The IDI is focused on time (compared to the IVI, focused on value), represents an intuitive concept and behaves in a linear way. The joint analysis of IVI and IDI provides results in a more complete understanding of the state of the assets, while maintaining the simplicity of the tools. The Infrastructure Histogram allows for a full evaluation of the infrastructure state and provides a detailed picture of network age compared to its expected life, as well as an order of magnitude of the required investments in the following years.Cabrera Rochera, E.; Estruch-Juan, ME.; Gomez Selles, E.; Del Teso-March, R. (2019). Defining complementary tools to the IVI. The Infrastructure Degradation Index (IDI) and the Infrastructure Histogram (HI). Urban Water Journal. 16(5):343-352. https://doi.org/10.1080/1573062X.2019.1669195S343352165Alegre, H., Vitorino, D., & Coelho, S. (2014). Infrastructure Value Index: A Powerful Modelling Tool for Combined Long-term Planning of Linear and Vertical Assets. Procedia Engineering, 89, 1428-1436. doi:10.1016/j.proeng.2014.11.469Amaral, R., Alegre, H., & Matos, J. S. (2016). A service-oriented approach to assessing the infrastructure value index. Water Science and Technology, 74(2), 542-548. doi:10.2166/wst.2016.250Aware-p.org. 2014. “AWARE-P/Software.” Accessed 25 November 2018. http://www.aware-p.org/np4/software/Baseform. 2018. “Baseform.” Accessed 24 November 2018. https://baseform.com/np4/productCanal de Isabel II Gestión. 2012. Normas Para Redes de Abastecimiento. [Standards for Water Supply Networks.]. https://www.canalgestion.es/es/galeria_ficheros/pie/normativa/normativa/Normas_redes_abastecimiento2012_CYIIG.pdfFrost, and Sullivan. 2011. “Western European Water and Wastewater Utilities Market.” https://store.frost.com/western-european-water-and-wastewater-utilities-market.html#section1Leitão, J. P., Coelho, S. T., Alegre, H., Cardoso, M. A., Silva, M. S., Ramalho, P., … Carriço, N. (2014). Moving urban water infrastructure asset management from science into practice. Urban Water Journal, 13(2), 133-141. doi:10.1080/1573062x.2014.939092Marchionni, V., Cabral, M., Amado, C., & Covas, D. (2016). Estimating Water Supply Infrastructure Cost Using Regression Techniques. Journal of Water Resources Planning and Management, 142(4), 04016003. doi:10.1061/(asce)wr.1943-5452.0000627Marchionni, V., Lopes, N., Mamouros, L., & Covas, D. (2014). Modelling Sewer Systems Costs with Multiple Linear Regression. Water Resources Management, 28(13), 4415-4431. doi:10.1007/s11269-014-0759-zPulido-Velazquez, M., Cabrera Marcet, E., & Garrido Colmenero, A. (2014). Economía del agua y gestión de recursos hídricos. Ingeniería del agua, 18(1), 95. doi:10.4995/ia.2014.3160Rokstad, M. M., Ugarelli, R. M., & Sægrov, S. (2015). Improving data collection strategies and infrastructure asset management tool utilisation through cost benefit considerations. Urban Water Journal, 13(7), 710-726. doi:10.1080/1573062x.2015.102469

Nutrient recovery in wastewater treatment plants: Comparative assessment of different technological options for the metropolitan region of Buenos Aires

In the metropolitan region of Buenos Aires, the load of nutrients discharged to urban rivers and shores is producing a severe eutrophication problem in the estuary of La Plata River. That problem could be alleviated by recovering nitrogen (N) and phosphorus (P) through the production of fertilizer products in the existing activated sludge treatment plants. Four nutrient recovery options were considered: struvite precipitation in the centrate line; acidic leaching of the sludge followed by struvite precipitation of the centrate; Ion Exchange in the centrate line; and a combination of struvite precipitation in the centrate line plus an Ion Exchange unit to further polish the secondary effluent. Those options were compared with basis on their economic sustainability and their capacity to reduce the load of N and P discharged to the coastal waters and rivers. The economic assessment indicated that producing fertilizer products in the existing facilities, using the four considered options, would be unprofitable. In the best case, which is struvite precipitation in the centrate line, the potential revenues would only cover 38.5 % of the operational expenses. Environmental benefits could justify that cost, as in some urban rivers the load of P could be reduced by 42.5 % by struvite precipitation. Regarding the load of nutrients that is discharged to the estuary, the impact of the considered nutrient recovery options ranges from a decrease in 0.5 % N and 3.7 % P (struvite precipitation) to a decrease in 8.2 % N and 4.4 % P (combination of struvite precipitation + Ion Exchange)